In a fuel injection device of an engine, a fuel injection amount is adjusted in advance in order to suppress variation in the injection amount caused by individual differences. However, since this adjustment is insufficient, the injection amount may deviate from a proper value. Further, the injection amount may deviate from the proper value due to deterioration over time of the fuel injection device. In a case where a fuel is particularly injected larger than the proper value under these cases, fuel efficiency deteriorates and an emission increases.
JP2001-207897A discloses an abnormality detecting apparatus for detecting deviation of a fuel injection amount from a target fuel injection amount on the basis of whether a ratio between an exhaust gas temperature and an engine head temperature is within a proper temperature ratio range or not.